(function () {

    class WEBGL {

        static isWebGLAvailable() {

            try {

                const canvas = document.createElement('canvas');
                return !!(window.WebGLRenderingContext && (canvas.getContext('webgl') || canvas.getContext('experimental-webgl')));

            } catch (e) {

                return false;

            }

        }

        static isWebGL2Available() {

            try {

                const canvas = document.createElement('canvas');
                return !!(window.WebGL2RenderingContext && canvas.getContext('webgl2'));

            } catch (e) {

                return false;

            }

        }

        static getWebGLErrorMessage() {

            return this.getErrorMessage(1);

        }

        static getWebGL2ErrorMessage() {

            return this.getErrorMessage(2);

        }

        static getErrorMessage(version) {

            const names = {
                1: 'WebGL',
                2: 'WebGL 2'
            };
            const contexts = {
                1: window.WebGLRenderingContext,
                2: window.WebGL2RenderingContext
            };
            let message = 'Your $0 does not seem to support <a href="http://khronos.org/webgl/wiki/Getting_a_WebGL_Implementation" style="color:#000">$1</a>';
            const element = document.createElement('div');
            element.id = 'webglmessage';
            element.style.fontFamily = 'monospace';
            element.style.fontSize = '13px';
            element.style.fontWeight = 'normal';
            element.style.textAlign = 'center';
            element.style.background = '#fff';
            element.style.color = '#000';
            element.style.padding = '1.5em';
            element.style.width = '400px';
            element.style.margin = '5em auto 0';

            if (contexts[version]) {

                message = message.replace('$0', 'graphics card');

            } else {

                message = message.replace('$0', 'browser');

            }

            message = message.replace('$1', names[version]);
            element.innerHTML = message;
            return element;

        }

    }

    THREE.WEBGL = WEBGL;

})();